One mL of an organic compound was dissolved in ethanol and a very small drop of dilute alkali was added to it and them a drop of phenolphthalein was added. The red colour of the indicator was seen. Th

Question

One mL of an organic compound was dissolved in ethanol and a very small drop of dilute alkali was added to it and them a drop of phenolphthalein was added. The red colour of the indicator was seen. The mixture was then heated. The colour disappeared in a few minutes. The organic compound is most likely to be

TestHub · Accepted Answer

Phenolphthalein does not give any colour with a carboxylic acid containing a drop of dilute alkali.
The red colour of the indicator indicates that alkali remains un-reacted before heating the compound.
After heating, disappearance of red colour indicates the consumption of NaOH. This because the ester hydrolyses in presence of base to form alcohol and sodium salt of carboxylic acid.
$RCOOR' + NaOH \overset{Δ}{\to} RCOONa + R' OH$

Chemistry - Carboxylic acid and their Derivatives Question with Solution | TestHub

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